1. Field of the Invention
The present invention relates to a graphic processing system for automatically reconstructing the dimensional and geometric constraints of graphics.
In recent years, in computer aided design, increased use has been made of graphic processing systems with a parametric (variational) function. With this function, by defining the geometric constraints (horizontal, vertical, parallel, and other geometric constraints) and dimensions with respect to a graphic, when the value of a dimension is changed, the graphic is changed accordingly. Thanks to this function, it becomes possible to easily makes changes in design. Note that a "constraint" means the establishment of a condition arbitrarily determining the shape of a graphic to the system.
2. Description of the Related Art
Systems realizing the above-described parametric function have already been supplied for commercial use. Accordingly, the technique for realizing a parametric function per se does not cause any trouble in current systems.
However, when a user further edits a formed graphic, that is, a graphic for which the dimensional and geometric constraints have already been defined, the following trouble occurs.
The user often wants to further edit a formed graphic, that is, a graphic for which the dimensional and geometric constraints have been already defined. Here, "edit" means, as will be mentioned in detail later, further application of a fillet, chamfer, trimming, and so on to a part of the formed graphic. When such editing is carried out on the display of, for example, a CAD system using a pointing device, the contents of the dimensional and geometric constraints of the related graphic already defined in a table in the system no longer match with the contents of the dimensional and geometric constraints newly defined by the related graphic after editing. This being the case, if the parametric function is activated referring to the above-mentioned table, the correct desired graphic will not be formed.
In conventional systems, when further performing the above-described editing on a formed graphic, use was made of the procedure of:
(a) holding the contents of the above-described table as they were or PA1 (b) completely deleting (erasing), among the data in the above-described table, the data of the dimensional and geometric constraints concerning the graphic for which the above-described editing was carried out.
However, in a system adopting the procedure of the above-described (a), no longer matching data remains as it is in the table, and therefore when drawing the graphic by the parametric function after this, there is a possibility of a glaringly erroneous picture on the display. At this time, the user is forced to manually correct the data in the table causing the erroneous picture.
Accordingly, in a system adopting the procedure of the above-described (a), there are the problems that every time the above-described editing is carried out, the load on the user is large and the user is inconvenienced.
On the other hand, in a system adopting the procedure of the above-described (b), to re-activate the original parametric function, the user must newly reconstruct the data in the table concerning the edited graphic by manual operation.
Accordingly, in the system adopting the procedure of the above-described (b) as well, there are the problems that every time editing is carried out, the load on the user is large and the user is inconvenienced.